Has anyone not heard? Khomeini was supposed to be the 12th imam returned. Maybe that was a little premature. The moslem apocalypse is far more imaginative and detailed than anybody else's apocalypse.
He believes he's been chosen by Allah to bring about the return of the 12 Imam, which is the first sign of their version of the apocalypse. That's my understanding of it.
I didn't do a search on it - I am sure one would turn up lots of hits as that has been widely reported.